In SNA, the meanings of, and the sequencing rules for, requests and responses used for managing the network, transferring data, and synchronizing the states of network components.

• 在系统网络体系结构(SNA)中,为了管理网络、传送数据以及为网络各组成部件的状态建立同步所使用的请求和响应的含义和定序的规则。